The example of C2O4 illustrates the fact that unusual oxides of carbon have interesting and complex chemical behavior. From our experience with alpha- and beta-lactones, peroxides and polyoxides we propose synthesis and study of other new oxides of carbon containing some of these functional groups. When each such compound is made and characterized, it will be possible to determine under what conditions it may occur in nature. We wish to follow up our demonstration that oxygen of the air, through photosensitizers of different types, can produce epoxides as well as peroxides. We seek to understand the mechanism of the photoepoxidation and the extent to which, like the singlet oxygen reaction, it may occur in nature. This effort begins with studies of known photoepoxidations with isotopic tracers and by monochromatic photochemistry; it continues with studies of the effect of varying the structure of the substrate on the properties of the epoxidation and its products. An informative probe for this purpose should be the synthesis of a number of substrates which are artifically simplified in that small variations in the geometric state of the double bond are made without any accompanying changes in the nature of substituent groups that can complicate the chemistry. Once this has been done, it should become apparent what structures present in physiological systems are most prone to be photo-epoxidized. Finally it is an objective of this program to examine the quenchers and protective agents that may inhibit photo-epoxidation as singlet oxygen quenchers (e.g., beta-carotene) inhibit peroxide formation.